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Commit966970e

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Re-revert stats collector latch changes.
This reverts commitcb2f287, restoringthe latch-ified stats collector logic. We'll soon see if this works anybetter on the Windows buildfarm machines.
1 parentb85427f commit966970e

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1 file changed

+68
-117
lines changed

1 file changed

+68
-117
lines changed

‎src/backend/postmaster/pgstat.c

Lines changed: 68 additions & 117 deletions
Original file line numberDiff line numberDiff line change
@@ -28,12 +28,6 @@
2828
#include<arpa/inet.h>
2929
#include<signal.h>
3030
#include<time.h>
31-
#ifdefHAVE_POLL_H
32-
#include<poll.h>
33-
#endif
34-
#ifdefHAVE_SYS_POLL_H
35-
#include<sys/poll.h>
36-
#endif
3731

3832
#include"pgstat.h"
3933

@@ -55,8 +49,8 @@
5549
#include"storage/backendid.h"
5650
#include"storage/fd.h"
5751
#include"storage/ipc.h"
52+
#include"storage/latch.h"
5853
#include"storage/pg_shmem.h"
59-
#include"storage/pmsignal.h"
6054
#include"storage/procsignal.h"
6155
#include"utils/ascii.h"
6256
#include"utils/guc.h"
@@ -94,9 +88,6 @@
9488
* failed statistics collector; in
9589
* seconds. */
9690

97-
#definePGSTAT_SELECT_TIMEOUT2/* How often to check for postmaster
98-
* death; in seconds. */
99-
10091
#definePGSTAT_POLL_LOOP_COUNT(PGSTAT_MAX_WAIT_TIME / PGSTAT_RETRY_DELAY)
10192
#definePGSTAT_INQ_LOOP_COUNT(PGSTAT_INQ_INTERVAL / PGSTAT_RETRY_DELAY)
10293

@@ -139,6 +130,8 @@ PgStat_MsgBgWriter BgWriterStats;
139130
*/
140131
NON_EXEC_STATICpgsocketpgStatSock=PGINVALID_SOCKET;
141132

133+
staticLatchpgStatLatch;
134+
142135
staticstructsockaddr_storagepgStatAddr;
143136

144137
statictime_tlast_pgstat_start_time;
@@ -3009,15 +3002,7 @@ PgstatCollectorMain(int argc, char *argv[])
30093002
{
30103003
intlen;
30113004
PgStat_Msgmsg;
3012-
3013-
#ifndefWIN32
3014-
#ifdefHAVE_POLL
3015-
structpollfdinput_fd;
3016-
#else
3017-
structtimevalsel_timeout;
3018-
fd_setrfds;
3019-
#endif
3020-
#endif
3005+
intwr;
30213006

30223007
IsUnderPostmaster= true;/* we are a postmaster subprocess now */
30233008

@@ -3036,9 +3021,13 @@ PgstatCollectorMain(int argc, char *argv[])
30363021
elog(FATAL,"setsid() failed: %m");
30373022
#endif
30383023

3024+
/* Initialize private latch for use by signal handlers */
3025+
InitLatch(&pgStatLatch);
3026+
30393027
/*
30403028
* Ignore all signals usually bound to some action in the postmaster,
3041-
* except SIGQUIT.
3029+
* except SIGHUP and SIGQUIT. Note we don't need a SIGUSR1 handler to
3030+
* support latch operations, because pgStatLatch is local not shared.
30423031
*/
30433032
pqsignal(SIGHUP,pgstat_sighup_handler);
30443033
pqsignal(SIGINT,SIG_IGN);
@@ -3073,26 +3062,24 @@ PgstatCollectorMain(int argc, char *argv[])
30733062
pgStatRunningInCollector= true;
30743063
pgStatDBHash=pgstat_read_statsfile(InvalidOid, true);
30753064

3076-
/*
3077-
* Setup the descriptor set for select(2).Since only one bit in the set
3078-
* ever changes, we need not repeat FD_ZERO each time.
3079-
*/
3080-
#if !defined(HAVE_POLL)&& !defined(WIN32)
3081-
FD_ZERO(&rfds);
3082-
#endif
3083-
30843065
/*
30853066
* Loop to process messages until we get SIGQUIT or detect ungraceful
30863067
* death of our parent postmaster.
30873068
*
3088-
* For performance reasons, we don't want to do a PostmasterIsAlive() test
3089-
* after every message; instead, do it only when select()/poll() is
3090-
* interrupted by timeout.In essence, we'll stay alive as long as
3091-
* backends keep sending us stuff often, even if the postmaster is gone.
3069+
* For performance reasons, we don't want to do ResetLatch/WaitLatch after
3070+
* every message; instead, do that only after a recv() fails to obtain a
3071+
* message. (This effectively means that if backends are sending us stuff
3072+
* like mad, we won't notice postmaster death until things slack off a
3073+
* bit; which seems fine.) To do that, we have an inner loop that
3074+
* iterates as long as recv() succeeds. We do recognize got_SIGHUP inside
3075+
* the inner loop, which means that such interrupts will get serviced but
3076+
* the latch won't get cleared until next time there is a break in the
3077+
* action.
30923078
*/
30933079
for (;;)
30943080
{
3095-
intgot_data;
3081+
/* Clear any already-pending wakeups */
3082+
ResetLatch(&pgStatLatch);
30963083

30973084
/*
30983085
* Quit if we get SIGQUIT from the postmaster.
@@ -3101,87 +3088,37 @@ PgstatCollectorMain(int argc, char *argv[])
31013088
break;
31023089

31033090
/*
3104-
* Reload configuration if we got SIGHUP from the postmaster.
3105-
*/
3106-
if (got_SIGHUP)
3107-
{
3108-
ProcessConfigFile(PGC_SIGHUP);
3109-
got_SIGHUP= false;
3110-
}
3111-
3112-
/*
3113-
* Write the stats file if a new request has arrived that is not
3114-
* satisfied by existing file.
3091+
* Inner loop iterates as long as we keep getting messages, or until
3092+
* need_exit becomes set.
31153093
*/
3116-
if (last_statwrite<last_statrequest)
3117-
pgstat_write_statsfile(false);
3118-
3119-
/*
3120-
* Wait for a message to arrive; but not for more than
3121-
* PGSTAT_SELECT_TIMEOUT seconds. (This determines how quickly we will
3122-
* shut down after an ungraceful postmaster termination; so it needn't
3123-
* be very fast. However, on some systems SIGQUIT won't interrupt the
3124-
* poll/select call, so this also limits speed of response to SIGQUIT,
3125-
* which is more important.)
3126-
*
3127-
* We use poll(2) if available, otherwise select(2). Win32 has its own
3128-
* implementation.
3129-
*/
3130-
#ifndefWIN32
3131-
#ifdefHAVE_POLL
3132-
input_fd.fd=pgStatSock;
3133-
input_fd.events=POLLIN |POLLERR;
3134-
input_fd.revents=0;
3135-
3136-
if (poll(&input_fd,1,PGSTAT_SELECT_TIMEOUT*1000)<0)
3137-
{
3138-
if (errno==EINTR)
3139-
continue;
3140-
ereport(ERROR,
3141-
(errcode_for_socket_access(),
3142-
errmsg("poll() failed in statistics collector: %m")));
3143-
}
3144-
3145-
got_data= (input_fd.revents!=0);
3146-
#else/* !HAVE_POLL */
3147-
3148-
FD_SET(pgStatSock,&rfds);
3149-
3150-
/*
3151-
* timeout struct is modified by select() on some operating systems,
3152-
* so re-fill it each time.
3153-
*/
3154-
sel_timeout.tv_sec=PGSTAT_SELECT_TIMEOUT;
3155-
sel_timeout.tv_usec=0;
3156-
3157-
if (select(pgStatSock+1,&rfds,NULL,NULL,&sel_timeout)<0)
3094+
while (!need_exit)
31583095
{
3159-
if (errno==EINTR)
3160-
continue;
3161-
ereport(ERROR,
3162-
(errcode_for_socket_access(),
3163-
errmsg("select() failed in statistics collector: %m")));
3164-
}
3096+
/*
3097+
* Reload configuration if we got SIGHUP from the postmaster.
3098+
*/
3099+
if (got_SIGHUP)
3100+
{
3101+
got_SIGHUP= false;
3102+
ProcessConfigFile(PGC_SIGHUP);
3103+
}
31653104

3166-
got_data=FD_ISSET(pgStatSock,&rfds);
3167-
#endif/* HAVE_POLL */
3168-
#else/* WIN32 */
3169-
got_data=pgwin32_waitforsinglesocket(pgStatSock,FD_READ,
3170-
PGSTAT_SELECT_TIMEOUT*1000);
3171-
#endif
3105+
/*
3106+
* Write the stats file if a new request has arrived that is not
3107+
* satisfied by existing file.
3108+
*/
3109+
if (last_statwrite<last_statrequest)
3110+
pgstat_write_statsfile(false);
31723111

3173-
/*
3174-
* If there is a message on the socket, read it and check for
3175-
* validity.
3176-
*/
3177-
if (got_data)
3178-
{
3112+
/*
3113+
* Try to receive and process a message. This will not block,
3114+
* since the socket is set to non-blocking mode.
3115+
*/
31793116
len=recv(pgStatSock, (char*)&msg,
31803117
sizeof(PgStat_Msg),0);
31813118
if (len<0)
31823119
{
3183-
if (errno==EINTR)
3184-
continue;
3120+
if (errno==EAGAIN||errno==EWOULDBLOCK||errno==EINTR)
3121+
break;/* out of inner loop */
31853122
ereport(ERROR,
31863123
(errcode_for_socket_access(),
31873124
errmsg("could not read statistics message: %m")));
@@ -3279,17 +3216,21 @@ PgstatCollectorMain(int argc, char *argv[])
32793216
default:
32803217
break;
32813218
}
3282-
}
3283-
else
3284-
{
3285-
/*
3286-
* We can only get here if the select/poll timeout elapsed. Check
3287-
* for postmaster death.
3288-
*/
3289-
if (!PostmasterIsAlive())
3290-
break;
3291-
}
3292-
}/* end of message-processing loop */
3219+
}/* end of inner message-processing loop */
3220+
3221+
/* Sleep until there's something to do */
3222+
wr=WaitLatchOrSocket(&pgStatLatch,
3223+
WL_LATCH_SET |WL_POSTMASTER_DEATH |WL_SOCKET_READABLE,
3224+
pgStatSock,
3225+
-1L);
3226+
3227+
/*
3228+
* Emergency bailout if postmaster has died. This is to avoid the
3229+
* necessity for manual cleanup of all postmaster children.
3230+
*/
3231+
if (wr&WL_POSTMASTER_DEATH)
3232+
break;
3233+
}/* end of outer loop */
32933234

32943235
/*
32953236
* Save the final stats to reuse at next startup.
@@ -3304,14 +3245,24 @@ PgstatCollectorMain(int argc, char *argv[])
33043245
staticvoid
33053246
pgstat_exit(SIGNAL_ARGS)
33063247
{
3248+
intsave_errno=errno;
3249+
33073250
need_exit= true;
3251+
SetLatch(&pgStatLatch);
3252+
3253+
errno=save_errno;
33083254
}
33093255

33103256
/* SIGHUP handler for collector process */
33113257
staticvoid
33123258
pgstat_sighup_handler(SIGNAL_ARGS)
33133259
{
3260+
intsave_errno=errno;
3261+
33143262
got_SIGHUP= true;
3263+
SetLatch(&pgStatLatch);
3264+
3265+
errno=save_errno;
33153266
}
33163267

33173268

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